Assign 16-1 - Organic Chem 2 Assign 16-1 1 Draw and describe A Kekule's proposed structure for benzene What is the geometry of this structure What does

Organic Chem 2 Assign 16-1 1. Draw and describe A. Kekule's proposed structure for benzene. What is the geometry of this structure? What does his structure predict with respect to relative carbon-carbon bond lengths? 2. What chemical behavior would you expect for the Kekule structure of benzene? 3. What do modern measurements indicate about the structure and geometry of benzene? Briefly describe the observed chemical behavior of benzene. What is the observed stability of benzene? 4. Draw and describe the valence-bond (conjugated p orbitals) model of benzene. Does this model completely account for the observed stability of benzene? 5. In terms of molecular orbital theory, why is benzene so stable? 6. Why does benzene tend to undergo substitution reactions rather than addition reactions? 7. List several of the observed physical and chemical properties of aromatic compounds (species). 8. Using the "polygon-on-a-corner" method, draw an MO energy diagram for each of the following species. On the basis of your diagram, determine if the species is aromatic or nonaromatic.